Passive House

In the August 2008 issue, Journal of Light Construction published an article titled: Making the best of rising energy costs, by Paul Eldrenkamp. In his article, Paul talkes about different building standards, one of which is Passive House. Paul also addresses one of my biggest issues with “green” building — the leck of emphasis on energy! I could not agree more that we can do so much better in terms of performance of buildings.
While Energy Star and LEED offer a potential 25% reduction in energy consumption over code-construction, Passive House uses energy modeling and field-testing to deliver up to 90% reduced energy consumption for space conditioning, and a 75% reduction in overall source-energy consumption. All of this at a very small increase in day-one construction cost, which are easily offset in a very short amount of time, while creating real value, increased sale or resale prices, and up to 25% quicker sales.
Passive House retrofits offer the potential of reducing energy consumption for space-conditioning by up to 80%. This is still much more than a LEED conversion would yield. Nevertheless, LEED can be a great partner, as many of its requirements compliment Passive House standard quite well.
So, enjoy Paul’s article and consider energy when looking at your next project, no matter what the type or budget may be. Improvements can be made at any step along the way. And the benefit is always yours.

I added a page for lectures and talks to the navigation menu on the right hand side, under Pages. In addition I created a page that holds all the metrics regarding Passive House design, as well as some recommendations, opportunities and links to resources. I thought it may be helpful to have it all in one place.

I am currently working on a strategy for a dehumidification system for the Appleseed House in Minneapolis, MN. There are a few weeks out of any given year that make dehumidification a necessity. Most Minnesotans agree that the humidity is what makes July and August unpleasant, rather than the temperature. During the Passive House Consultant’s training I was able to spend some time with David White from Transsolar on the subject. We identified one strategy that uses a Thermastor UA-XT150H dehumidification machine (see image) that can be added to the airflow at those times of the year. In further discussion with Thermastor I learned that I actually have options on how to use their equipment. The original idea that David and I discussed was to utilize a ground-loop to run a water-cooled coil in the Thermastor machine. In this case, heat generated in the process would be deposited in the ground. A way to put that energy to better use would be to run a loop through a DHW storage tank. Alternatively, the machine could be run without the condensing coil inside, and simply exhaust to the exterior. Further investigation is needed to make the proper choice. I also learned from Thermastor that the machine David and I were looking at is likely oversized. Thermastor does offer smaller capacity units that may be more fitting for my particular application. The water-cooled coil is a special order version of the XT150H.

During this last session of Passive House Training I learned that 25-35kWh per square meter and year are acceptable, and respectable space-conditioning energy numbers for a remodeled building. At the same time, any other requirements like air-tightness do not differ from the original Passive House requirements. While a remodel that achieves 25-35 kWh per square meter and year does not pass PHPP (Passive House Planning Package) calculations, it is a substantial achievement and definitely a significant improvement over performance before the upgrade (potentially up to 80% and more energy saved).

The Passive House Institute has researched and shown, that there is tremendous value in retrofitting to Passive House standard. Adding Passive House insulation and achieving high air-tightness helps avoid condensation and due-points at the thermal bridges and inside wall assemblies, therefore protecting the existing structure far better than a lesser improvement. This also ensures healthier indoor environmental quality.

I have seen a great number of air-intakes for ventilation systems here in the US that all look alike: A duct protruding a wall; sometimes with a grille to keep debris out, sometimes cut at an angle or decorated to stand out as an architectural gesture. (FYI, the lip shown above in the image is the underside of an exterior metal window sill.)

Air Intake

During my visit to Germany I came across this intake, that also doubles as a filter for pollen and particles. I thought this was a neat idea and worth replicating, even if the design of the box could use a little bit of design attention. The filters in HRV or ERV machines are not really meant to take care of these pollutants and by the time they get to the equipment, they are already inside the duct-system. I have yet to locate a resource for such a product in the US—the model shown is made by a company named Paul in Germany.

I am in Urbana, IL this week to complete the third round of the first ever US Passive House seminar. At this point there is a core group of people that is going for certification. The conversations and discussions are exciting and inspiring. Today’s exercise actually revolved around the Waldsee Biohaus in Bemidji, MN. I have not been up there—unfortunately a trip with the MinneApplessed group had to be cancelled—but I have met with the architect Stefan Tanner to learn a little bit about its conception and construction. I am going to miss Urbana after this session, and the people that come here to become Passive House pioneers and make history 😉 Fortunately, some of them will come to Duluth in November, so that conversations and discussions can be continued and experience be shared. At this point it is only appropriate to thank Katrin Klingenberg and Mike Kernagis for their relentless effort to bring Passive House to the US and share their wisdom with those who will bring it to the masses.

I am all fired up after my trip to Germany and the studies of a few Passive Houses in the birthplace of Passive House design. Along those lines I don’t want to forget to mention that this year’s annual North American Passive House Conference is right around the corner. PHIUS (Passive House Institute US) is hosting the third annual conference right in our backyard, in Duluth, MN. Click on the image below for the conference website. I am signed up for the conference and tour, in case you would like to hook up with me up north. This is the place to be for everything Passive House in North America.

I’m posting from Gotha (Germany) today. Over the course of the last two weeks I explored a couple of Passive Houses and carefully studied the latest and greatest strategies and details. The images below show a coupe of projects I toured, as well as one that caught my attention along the way. I look forward to implementing the recent experience into my current work.

Most energy sources’ embodied energy is diminished by the time it is delivered to and consumed in your home. For example, the energy that is embodied in a piece of coal that is used in a coal-fired power plant to generate electricity is roughly diminished by up to 70% by the time it reaches an electrical outlet in your home through inefficiencies both in the production of electricity and in the transmitting power grid. It is important to take this into account when making choices for what energy source to consider for a building. In terms of electricity, I can recommend Xcel’s wind-source program for the TwinCities, as it’s production does not produce carbon emissions. Nevertheless, transmission losses are an issue here as well. On-site solar photo-voltaic systems can be a great option to eliminate high primary energy use. The best solution will depend on the location and solar exposure of your building.
In the Passive House calculations, primary energy is calculated using factors that describe inefficiencies and energy loss as opposed to just looking at the energy use in the building. Passive House standard limits this primary energy use to 31,700 BTUs per square foot of living space and year, or 120kWh per square meter and year in the metric system.

A couple of days ago I attended an AIA breakfast seminar by speaker Louise Goldberg, Senior Research Associate and Director Building Physics and Foundations Research Programs at the College of Design, University of Minnesota—that is a mouth-full, I know. Louise has done extensive research in the field of wall-system performance, or in simpler terms, ways to keep the water out and the space-conditioning heat and cold in. Louise made a point of demonstrating a Universal Standard (that she proposes) versus MN Energy Code. In my opinion this is highly relevant research, and Louise offers practical solutions for exterior wind wash barriers, water separation planes, air barriers, vapor retarders and insulation—all with research data to back it up. If you want to get technical you can find one of her research reports at this address. I am meeting with Louise this month to discuss wall systems for Passive House designs. Louise is a Ph.D (Eng) and her company —Lofrango Engineering— offers consulting services.
A thing of interest for Passive House designers is the fact that Louise talked about the benefits of wood fiberboard sheathing for stud-wall construction, as well as structural 1.5″ OSB stacked wood wall panels. I have yet to find more info on these wall systems. I think that the U of M did research on developing a stacked wood wall system, so if anyone has a link to that, please comment.

Peak Building Products out of Watertown, MN is now offering Optiwin windows from Germany. Thermally broken frames and heavy duty construction put them up there with the best windows in the world. Their products are Passive House certified by the Passive House Institute but their unmatched R-values of 10 and better make them a great choice for any type of construction in climate zones with above average heating or cooling loads. Optiwin also offers glazing options that allow for passive solar heat gains, which are desirable in heating climates such as Minnesota. Find out more at www.optiwin-usa.com, or at www.peakbp.net
Before I forget, Optiwin also makes a stunning entrance door called the “Frostkorken Door”. Again, the R-value performance is incredible. In recent calculations I found that the entrance door to an average size residence alone can have significant impact on the heat loss.

I have seen a lot of these “Your Speed” Police displays around the Twin Cities lately, and while I think that they are a good idea, I feel that we are in desperate need of displays that tell us what our “environmental speed” is.

Now I know, some people think that we are scolding people by showing them how much gas their vehicle burns or how much CO2 comes out of the tail pipe. Nevertheless, how is one to conserve if he Read more →

The Passive House standard was originally developed in Germany, inspired by American pioneers like Wayne Schick and William Shurcliff, who explored the idea of making extremely energy-efficient buildings in the late 1970s and early 80s. The standard is now widely accepted throughout Europe, following a pilot program called Cepheus (Cost Efficient Passive Houses as EUropean Standards) in 2000, and the Germans are looking to make it building code in 2020. The Passive House Institute in Germany is the official authority of the standard worldwide. It was co-founded in 1996 by Dr. Wolfgang Feist at the University of Darmstadt. In late 2007, the standard was introduced in the U.S. with the launch of the Passive House Institute U.S. (PHIUS). Since the standard has its roots in Europe, all energy modeling is done in metric format. This does not mean that it conflicts with building codes or construction methods in the U.S., as the numbers can be converted to the American standard and back. The important number to remember here is 15kWh per square meter and year (4,750BTU per square foot and year), which means up to 90% less energy used for space conditioning, i.e. heating and cooling.